U.S. patent number 10,816,074 [Application Number 15/048,241] was granted by the patent office on 2020-10-27 for actuator mechanism.
This patent grant is currently assigned to GOODRICH ACTUATION SYSTEMS LIMITED, GOODRICH AEROSPACE SERVICES PRIVATE LIMITED. The grantee listed for this patent is Goodrich Actuation Systems Limited. Invention is credited to David John Langford, Narendran Muralidharan, Navaneethakrishnan Pandian.
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United States Patent |
10,816,074 |
Pandian , et al. |
October 27, 2020 |
Actuator mechanism
Abstract
An actuator system comprising a rotatable lock mechanism
defining a path for an actuator pin as the actuator is expanded and
retracted, wherein the lock mechanism defines an entry passage
through which the pin enters as the actuator extends, a guide
surface along which the pin travels from the entry passage as the
actuator retracts, a locking recess into which the pin is guided by
the guide surface, and an exit passage into which the pin is guided
as it is caused to leave the lock recess by extension of the
actuator and subsequent retraction; whereby a detent surface is
provided to prevent the pin returning back into the lock recess
when the actuator is extended to cause the pin to leave the lock
recess; and whereby the lock mechanism provides a sloping
engagement surface for the pin, either side of the entry
passage.
Inventors: |
Pandian; Navaneethakrishnan
(Karnataka, IN), Muralidharan; Narendran (Tamilnadu,
IN), Langford; David John (Wolverhampton,
GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
Goodrich Actuation Systems Limited |
Solihull, West Midlands |
N/A |
GB |
|
|
Assignee: |
GOODRICH ACTUATION SYSTEMS
LIMITED (West Midlands, GB)
GOODRICH AEROSPACE SERVICES PRIVATE LIMITED (Bangalore,
Karnataka, IN)
|
Family
ID: |
1000005141733 |
Appl.
No.: |
15/048,241 |
Filed: |
February 19, 2016 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20160245387 A1 |
Aug 25, 2016 |
|
Foreign Application Priority Data
|
|
|
|
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Feb 19, 2015 [EP] |
|
|
15155762 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E05F
15/53 (20150115); F16H 53/02 (20130101); F15B
15/261 (20130101); E05F 15/611 (20150115); B64D
29/06 (20130101); E05Y 2900/502 (20130101); E05Y
2201/638 (20130101); E05Y 2201/42 (20130101) |
Current International
Class: |
F16H
53/02 (20060101); E05F 15/53 (20150101); B64D
29/06 (20060101); F15B 15/26 (20060101); E05F
15/611 (20150101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
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2532821 |
|
Dec 2012 |
|
EP |
|
2666111 |
|
Feb 1992 |
|
FR |
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Other References
European Search Report for application No. EP15155762.6; dated Aug.
26, 2015, 6 pages. cited by applicant.
|
Primary Examiner: Rogers; Adam D
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
The invention claimed is:
1. An actuator system having a first end and a second end
comprising: a first eye at the first end; a second eye at the
second end; a cylindrical housing running between the first and
second end; an actuator rod slidably mounted within the housing; an
actuator pin; a fluid port that passes through the housing near the
first end of the housing through which fluid can be provided; a
rotatable lock mechanism provided at an end of the actuator rod and
being fixed to move axially with the actuator rod, wherein the
actuator pin is mounted on and extends through a wall of the
cylindrical housing at a location between the fluid port and second
end of the cylindrical housing, the rotatable lock mechanism having
channels formed therein that form for the actuator pin as the
actuator rod is extended and retracted, wherein the rotatable lock
mechanism has an entry passage having two sides through which the
actuator pin enters as the actuator rod extends, a guide surface
along which the actuator pin travels from the entry passage as the
actuator rod retracts, a locking recess into which the actuator pin
is guided by the guide surface, and an exit passage into which the
actuator pin is guided as the actuator pin is caused to leave the
lock recess by extension of the actuator rod and subsequent
retraction; a first detent finger provided in the entry passage
that blocks a return of the actuator pin back into the entry
passage after the actuator pin has passed over the first detent
finger; and wherein a second detent finger is provided on the
rotatable lock mechanism between the lock recess and the exit
passage which operates to block a return of the actuator pin back
into the lock recess after the actuator pin has left the lock
recess, so as to prevent the actuator pin from returning back into
the lock recess when the actuator rod is extended to cause the
actuator pin to leave the lock recess; wherein the second detent
finger comprises a sloping engagement surface on both of the two
sides of the entry passage against which the actuator pin abuts as
the actuator rod extends.
2. The system of claim 1, wherein the rotatable lock mechanism
comprises a collar within which the channels are formed and an
interlocking ring on which the first and second detent fingers
provided.
3. The system of claim 2, further comprising: a spring biased
detent ball arrangement biased across an inner circumference of the
interlocking ring.
Description
FOREIGN PRIORITY
This application claims priority to European Patent Application No.
15155762.6 filed Feb. 19, 2015, the entire contents of which is
incorporated herein by reference.
TECHNICAL FIELD
The present invention relates to an actuator mechanism moveable
between a locked and an unlocked position. The mechanism is
particularly, but not exclusively, for use in aircraft engines, and
finds particular application in opening and closing aircraft engine
cowls.
BACKGROUND OF THE INVENTION
Aircraft engine cowls such as those covering the C-duct and fans
need to be opened occasionally to allow access to the engine for
e.g. repair and maintenance, and then closed again. Actuators are
provided to open and close the cowls. Preferably no pressure or
driving force should be required to keep the actuator in the open
position, despite the weight of the cowl door.
Conventionally, hydraulic or pneumatic actuators are used, although
other types of actuator, e.g. electrical or mechanical, may also be
used. The actuators generally comprise an extendible rod or arm
that is attached to open the cowl as it extends and close the cowl
as it retracts under the weight of the cowl door.
A typical hydraulic actuator comprises a piston rod, a cylinder and
a rotatable lock mechanism to facilitate mechanical operation of
the cowl door or flap. Pressure is applied to fully extend the
actuator; when fully extended, pressure is removed allowing the
actuator to retract by a small amount which causes the actuator to
lock, as the lock mechanism rotates and engages the activator. To
close, or stow, the cowl door, the actuator is then extended by
application of pressure out of the locked position to its fully
extended position from which, as pressure is removed, the actuator
is able to return to a retracted, stowed, position.
A rotatable lock mechanism, in cooperation with a lock pin,
provides the paths for the actuator to take up its locked position
or return to its stowed position, as will be described further
below.
Whilst such an arrangement permits locking of the actuator in an
extended position, and so does not require the associated hydraulic
pump to be operating throughout the period of time that the
associated door or doors are to be held in their open positions,
there is a risk that if the actuator has not fully extended before
being retracted by a small amount to take up the locked state, the
actuator may come to rest in an intermediate position and appear to
be locked in its extended position without the locking mechanism
being properly engaged. In such circumstances, after the hydraulic
pressure has been removed, jarring or vibrations could result in
disengagement of the lock arrangement and the actuator being unable
to hold the door(s) in the open position. Clearly, this is
undesirable.
EP 2532821 describes an improved actuator mechanism that avoids the
actuator stopping in such an intermediate position. EP 2532821
provides a resilient detent in the paths for a locking pin provided
by the lock mechanism such that once the locking pin has moved
beyond a predetermined position in the extending direction the
resilient detent prevents return movement of the pin along the
entry path.
A further problem has been identified with the known actuator
mechanism when the actuator is used to return the cowl to the
stowed state. Here, as mentioned above, the actuator is extended
(out of the locked state) and then, due to the paths defined by the
lock mechanism, returns to the retracted state, via an exit path.
If, however, the actuator is not fully or sufficiently extended to
clear the path for the locked state, the pin can again become stuck
in position at an intermediate point, rather than automatically
feed into and follow the exit path under the weight of the cowl.
This intermediate position can be falsely interpreted as a locked
state. If the actuator is jolted or slightly disturbed, the locking
pin can slip from the intermediate point, back into the locked
position, which can damage the door as well as damage other parts
or cause injury.
Systems such as described in EP '821 include a feature that
prevents this problem to some extent. A spring biased detent ball
retainer (described further below) ensures that before the actuator
locks onto such an intermediate point, the detent ball which is
timed to run over a cam-like profile, rotates the collar lock so
that the lock pin either moves into the locked state or the
unlocked state.
Reliance of the lock mechanism on the torque generated by the
spring biased detent ball, however, limits the degrees of angular
deviation at which the actuator can operate. Torque generated by
the spring biased detent ball shall always be greater than the
varying resistive torque. The torque generated is highly sensitive
to the cam like profile the detent ball traces. The resistive
torque depends upon factors such as thickness of the thin fluid
film between the piston and lock collar (clearance), viscous drag
on surfaces of rotating components, viscosity of working fluid
which is, in turn, a function of ambient temperature.
The present invention therefore aims to provide an actuator locking
mechanism that can prevent the actuator becoming stuck in an
intermediate position when intended to be moved from the locked
position to the stowed position, without reliance on a spring
biased detent ball.
SUMMARY
The present invention, in one aspect, provides an actuator system
comprising a rotatable lock mechanism defining a path for an
actuator pin as the actuator is expanded and retracted, wherein the
lock mechanism defines an entry passage through which the pin
enters as the actuator extends, a guide surface along which the pin
travels from the entry passage as the actuator retracts, a locking
recess into which the pin is guided by the guide surface, and an
exit passage into which the pin is guided as it is caused to leave
the lock recess by extension of the actuator and subsequent
retraction; whereby a detent surface is provided to prevent the pin
returning back into the lock recess when the actuator is extended
to cause the pin to leave the lock recess.
In another aspect, the invention provides an actuator system
comprising a rotatable lock mechanism defining a path for an
actuator pin as the actuator is expanded and retracted, wherein the
lock mechanism defines an entry passage through which the pin
enters as the actuator extends, a guide surface along which the pin
travels from the entry passage as the actuator retracts, a locking
recess into which the pin is guided by the guide surface, and an
exit passage into which the pin is guided as it is caused to leave
the lock recess by extension of the actuator and subsequent
retraction; whereby the lock mechanism provides a sloping
engagement surface for the pin either side of the entry
passage.
In some embodiments, the guide surface and/or the detent surface
provide a slope.
A detent surface may also be provided in the entry passage.
The lock mechanism of the second aspect may provide advantages
alone or in combination with the detent of the first aspect.
The rotatable lock mechanism may comprise an interlocking collar
and gate ring combination whereby the detents are provided on a
gate ring that engages with the collar. Alternatively, the lock
mechanism may be an integral component.
A spring biased detent ball arrangement may be provided across the
inner surface of the lock mechanism.
BRIEF DESCRIPTION OF DRAWINGS
Preferred embodiments of the invention will now be described by way
of example only, and with reference to the drawings.
FIG. 1 shows an actuator according to an embodiment of the
invention, in use.
FIG. 2 shows a perspective view of an actuator according to the
invention.
FIG. 3 is a cut-away view of one end of the actuator of FIG. 2,
with the cylinder removed to aid description.
FIG. 4A shows the locking mechanism at the start of the locking
procedure.
FIG. 4B shows the detent ball mechanism in cross section at the
point shown in FIG. 4A.
FIGS. 5A to 17B show how the various components move relative to
each other during the locking and unlocking procedure.
FIG. 18A shows an improved locking mechanism according to another
aspect of the invention.
FIG. 18B is an exploded view of the locking mechanism of FIG.
18A.
FIGS. 19A to 31B show how the various components move relative to
each other during the locking and unlocking procedure.
DETAILED DESCRIPTION OF THE INVENTION
An existing actuator system will now be described with reference to
FIGS. 1 to 17.
FIG. 1 shows an actuator according to an embodiment of the
invention, in use. FIG. 1 shows part of an engine housing 10
including a door 12 moveable between a closed, in use position, and
an open position. In FIG. 1, the door 12 is shown in its open
position. An actuator 14 is arranged to drive the door (12) between
the two positions. In the example shown, the actuator is in the
form of a hydraulic piston or ram comprising a housing cylinder
(16) within which a piston (20) is slidable. The cylinder is
mounted to the engine housing 10, by means of an eye end (shown in
FIG. 2), while the door is connected to an end of the piston rod
(22), again via an eye end. By controlling the pressure of fluid
(24) applied to a chamber (18) within the actuator, extension and
retraction of the actuator can be controlled so as to drive the
door between its closed and opened positions. Other types of
actuators may be used, including electrically or mechanically
driven actuators.
As shown in more detail in FIGS. 2 and 3, the actuator comprises an
eye (50a, 50b) at each end for attachment, respectively, to the
engine and to the door to be opened and closed. A cylinder (51)
runs between the ends within which an piston rod (52) is axially
slidably mounted. A port (53) is provided through the cylinder
close to one end, through which fluid can be provided to
hydraulically move the piston rod within/along the cylinder. A
rotating lock mechanism (54) is provided at an end of the piston
(the end closest to the port when the piston is retracted within
the cylinder). The lock mechanism is fixed to move axially with the
piston rod and is rotatable within the cylinder. One or more
locking pins (55) are mounted on and extend through the cylinder
wall at a location between the fluid port and the opposite end of
the cylinder. As pressure is applied to the piston rod via the
fluid port, the rod, together with the lock mechanism, moves
axially away from the port, extending the actuator rod and moving
the lock mechanism towards the pin(s).
The lock mechanism defines a path for the locking pin(s) including
an entry passage, a locking recess, and an exit passage.
The lock mechanism comprises a collar lock 60 comprising a collar
having the path defined in its outer surface and, preferably,
grooves in e.g. a helical formation on its inner surface. A spring
biased detent ball arrangement (56) is biased across the inner bore
of the collar such that a spring biases balls to run in and out of
the grooves in the inner surface. The lock mechanism also comprises
guide surfaces to direct the pins along appropriate paths, and
detent means, as described above. These may be provided on one or
more gates or rings 62 that cooperate with the collar, or may be
formed as part of the collar itself.
As can be seen in FIGS. 4 to 17, as the actuator extends, the lock
mechanism engages the pin(s) in the cylinder, such that a pin
enters an entry passage 60 of the collar lock (FIGS. 4A, 4B). As
the actuator continues to extend, the pin moves into the entry
passage (FIGS. 5A, 5B) riding over a resilient detent finger 100
and pressing it down. After a certain degree of extension, the pin
has reached the end of the entry passage and passes over the detent
finger 100 which springs back to its raised position so that the
pin cannot return along the entry passage (FIGS. 6A, 6B). The
actuator is extended further, to its fully extended position.
Pressure is then removed from the piston rod (FIGS. 7A, 7B).
Removal of the pressure causes the piston rod to retract under the
weight of the attached door. The pin then engages and pushes
against a sloping guide surface 70 at the end of the entry
passageway (FIGS. 8A, 8B) which causes the collar lock to rotate,
and the spring based detent ball 200 travels into a groove, thus
guiding the pin along a path, and the actuator retracts a small
distance with the pin following a new path (FIGS. 9A, 9B). The pin
follows this path (FIGS. 10A, 10B) into a lock pocket 80 (FIGS.
11A, 11B) where it remains, holding the actuator, and thus the
door, in a locked open position.
To close the door, pressure is again applied to the piston to
extend it sufficient to move back out of the lock recess (FIGS.
12A, 12B) and to abut another sloping guide surface 90 (FIGS. 13A,
13B). The actuator is then fully extended (FIGS. 15A, 15B) after
which pressure is then removed causing the actuator to try to
retract (FIGS. 16A, 16B) which causes the pin to engage and press
against the sloping guide surface which causes further rotation of
the collar lock. The pin is guided into an exit passage 110 (FIGS.
17A, 17B) and is able to leave the collar via the exit passage due
to the weight of the door causing retraction of the actuator.
Resilient detent means are provided in the passages. As the pin
runs over these, it presses them down. Once the pin has passed over
the detent means, in some embodiments, the detent means springs
pack up preventing return of the pin and also preferably providing
a sloped guide surface.
As mentioned above, problems can arise if the actuator is not
extended enough for the pin to reach the sloped guide surface to
direct it to the next part of the path and into the locking recess.
This is shown in FIGS. 14A, 14B. The pins will, however, not pass
over the detent means or engage the sloping surfaces to rotate the
collar so the actuator will not reach its locked position but it
will retract to the stowed position rather than remaining `almost`
locked. The detent means prevent the actuator appearing, falsely,
to be locked when the locking procedure has not been completed
properly.
The spring biased detent ball 200 also helps to drive the actuator
into an end state (locked or stowed) rather than hanging at an
intermediate point (FIG. 14B). The reliability and extent of
support from the detent ball is, however, very limited, as
mentioned above.
The present invention provides an improved mechanism for preventing
the pin falling back into the locked position. FIG. 18A shows a
partial perspective view of an actuator according to the invention.
FIG. 18B is an exploded view of the locking mechanism. The
invention provides a resilient detent 120 at the exit of the
passage leading to the lock recess. This detent deflects down as
the pin rides over it as the actuator extends to release the lock
and, due to its resilience, springs up to form a detent once the
pin has passed over it. Thus, even if the actuator is not fully
extended, the pin is prevented from returning to the lock recess.
The detent is preferably also formed with a sloping surface or ramp
130 such that as the pin passes over the detent, and pressure is
removed, the pin rides along this ramp to cause rotation of the
collar lock and guide the pin into the exit passageway 140 from
which it exits the lock collar to retract the actuator.
The details of locking and unlocking operation of a system
according to the invention can be seen more clearly with reference
to FIGS. 19 to 31.
Similar to the locking and unlocking procedure described above with
reference to FIGS. 1 to 17, as the actuator is extended, the
locking pins come into engagement with the locking collar. In the
embodiment shown here, the surface of the locking collar with which
the pins first come into contact is sloped or helical, for reasons
described more below, as opposed to having long flat lands.
Otherwise, the locking and unlocking procedure is essentially as
described above.
The pins enter the entry passage 150 as the actuator is extended
(FIG. 20A). As the actuator continues to extend, the pin passes
over the resilient detent 120 at the end of the entry passage. As
the pin passes over the detent, it presses it down. The detent
returns to its raised position after the pin has cleared it,
preventing the pin returning back down the entry passage.
Once the actuator is fully extended, pressure is removed and the
actuator will retract a small distance. It will abut a sloped
surface 110', which may be formed by, or partially formed by the
raised detent. The pressure of the pin on the slope will cause
rotation of the collar relative to the pin, guiding the pin down
towards the lock recesses 160 (FIGS. 23, 24). The pin then rides
into the lock recess (FIG. 25) and comes to rest in the locked
position (FIG. 26). As the pin rides into the locked passage, it
passes over another resilient detent 170 which rises again after
the pin has cleared it to enter the lock recess.
To unlock the actuator, to stow the door, pressure is again applied
to the actuator to cause it to expand. The pin is forced out of the
lock recess 130' and over the detent 180', which again rises after
the pin has cleared it, to prevent the pin inadvertently returning
into the lock recess if the actuator is not sufficiently
extended.
The actuator is then fully extended (FIG. 27) after which pressure
is removed. The actuator then begins to retract under the weight of
the attached door. The pin abuts another sloping surface 180 (FIG.
28) which may be formed, or partially formed, by the detent,
causing the collar to rotate. The pin is guided around the collar
and into an exit passage 190 (FIG. 29) below the raised part of a
detent. The exit passage is preferably the same passage as the
initial entry passage.
The pin then exits the collar through the exit passage to fully
retract the actuator and stow the door.
As mentioned above, the spring biased detent ball 200' mechanism in
existing systems helps, to some extent, to prevent the locking
pin(s) hanging at a null point and appearing to be in a locked
position when the actuator is not, in fact, locked.
The spring biased detent ball mechanism can be seen in FIGS. 19B to
31B and comprises a spring 56' which biases two balls 200' at its
ends against the inner wall of the lock collar. This inner wall is
provided with a profile within which the balls travel as the collar
is caused to rotate by the locking pins engaging with the lock
collar outer path and passageways.
In addition to orienting the outer lock collar profile with respect
to the lock pins, the spring biased detent ball mechanism provides
an alignment mechanism in the event that the two eye ends (see FIG.
2) have been displaced, angularly, with respect to each other. If
this happens, the locking pin will not directly meet the entry
passage of the locking collar as the actuator is extended, but will
engage with the locking collar slightly to the side of the entrance
passage. Provided the angular displacement between the two eye ends
is fairly small (not more than around 5 or 6 degrees), the spring
biased detent ball will operate to rotate the collar such that the
pin is aligned with the entry passage. This works because, as can
be seen in FIG. 14B, the torque generated by the detent ball in the
groove provided inside the locking collar will quickly index the
collar lock back to its locked state.
Problems can, however, arise if the angular deviation between the
two eye ends is greater than, say, 5 or 6 degrees. The inner slope
over which the detent ball rides, inside the collar lock, cannot be
lengthened and, therefore, the detent ball would sit at a position
between the slopes and would not cause the automatic indexing
provided at smaller angular deviations.
Another feature of an aspect of the present invention provides a
solution to this problem and ensures, to a much greater degree,
that even with larger angular deviations between the eye ends, up
to around 45 degrees, the locking mechanism never hangs at a null
point.
The solution to this problem, provided by an aspect of the present
invention, is to provide a helical or sloping profile on the
surface of the locking collar that comes into engagement with the
locking pin(s).
In one example, there is an angular deviation of around 30 degrees.
Of course, other angles would also work.
In this example, it can be seen that as the actuator is extended,
the locking collar and the pins engage, but the pins do not meet
the locking collar at the entry passage as they would in the case
that the eye ends are properly aligned.
In the prior art systems, it could be the case that the pins engage
with a flat land of the locking collar such that the spring biased
detent ball mechanism is unable to rotate the collar to cause
indexing.
With the sloping profile of the locking collar of the invention,
however, the pin and sloping surface interact to cause rotation of
the locking collar relative to the pin until the pin reaches the
entry passage and the actuator locking mechanism then operates in a
way similar to that described above.
This aspect of the invention provides a greatly increased tolerance
to angular misalignment between the eye ends, without relying on
the spring biased detent ball mechanism. The spring biased detent
ball will still be provided to orient the helix profile on the
mechanism of the locking collar with respect to the lock pin and
retains the locking collar from rotating beyond a certain angle due
to vibration, when the actuator is at the stowed state.
This modification will ensure that the pin(s) does not ever meet
the locking collar at the flat land (which, in comparison to the
prior systems, is small) when extended, but the ball mechanism
cannot, as it can in the prior systems, cause a safety issue by
falsely indicating that the actuator is locked, due to the ball
being positioned at a null point.
In the most preferred system, this outer sloped or helical profile
is provided in combination with the spring-biased detent mechanism
provided at the end of the locking passage, to avoid false locking
or positioning. It is envisaged, however, that advantages could be
provided by the sloped profile per se.
* * * * *